1. Field of the Invention
The present invention relates to a multilayer electronic device for reducing an equivalent serial inductance (ESL) able to be used also as a capacitor array, particularly relates to a multiterminal multilayer capacitor.
2. Description of the Related Art
A capacitor is widely known as one kind of electronic devices. Along with CPUs and other devices becoming to have a higher frequency in recent years, multilayer ceramic chip capacitors having a small ESL have also come into use. As a multiterminal capacitor of the related art having a small ESL, those in the Japanese Unexamined Patent Publications No. 9-17693 and No. 11-144996 and the US Patent Publication U.S. Pat. No. 5,880,925 are known.
The multiterminal multilayer capacitors of the related art described in the publications are originally designed to have a capacitance, however, due to the configurations, they inevitably have parasitic inductance and that leads to an existence of equivalent serial inductance. Because an operation frequency becomes higher as an operation of an CPU becomes high speed in recent years, multiterminal multilayer capacitors having been used without any problems result in having too large parasitic inductance in some cases.
The present invention was made in consideration with the above circumstances and has as an object thereof to provide a multiterminal multilayer capacitor and other multilayer electronic devices capable of reducing equivalent serial inductance.
To attain the above object, according to a first aspect of the present invention, there is provided a multilayer electronic device, comprising:
a dielectric body formed by stacking dielectric layers;
a flat first internal electrode arranged in the dielectric body;
a flat second internal electrode arranged opposing to the first internal electrode and insulated via the dielectric layer in the dielectric body;
a first through-hole electrode connected to the first internal electrode by penetrating, penetrating the second internal electrode without connecting thereto and extending across these internal electrodes;
a second through-hole electrode connected to the second internal electrode.by penetrating, penetrating the first internal electrode without connecting thereto and extending across these internal electrodes;
a first terminal electrode arranged on an outer surface of the dielectric body and connected to the first through-hole electrode; and
a second terminal electrode arranged on the outer surface of the dielectric body and connected to the second through-hole electrode.
According to the multilayer electronic device of the present invention, two kinds of first and second through-hole electrodes alternately become anodes and cathodes when a current flows, and two kinds of first and second internal electrodes function as electrodes of a capacitor. Accordingly, magnetic flux generated by high frequency currents flowing inversely to each other in the two kinds of first and second through-hole electrodes cancels each other in the multilayer electronic device and is nullified. As a result, parasitic inductance in the multilayer electronic device itself is reduced, and thereby, equivalent serial inductance is reduced.
Also, in the present invention, since the internal electrodes and terminal electrodes are connected via the first and second through-hole electrodes in a pillar shape wherein the end portion has a large area, connection becomes firm between the first and second through-hole electrodes and the first and second terminal electrodes, and equivalent serial resistance (ESR) becomes low.
Preferably, a plurality of the first internal electrodes and a plurality of the second internal electrodes are respectively formed in the dielectric body; and
the first internal electrodes and the second internal electrodes are alternately arranged in the dielectric body.
In the case where a plurality of the first internal electrodes and a plurality of the second internal electrodes are formed and alternately arranged in the dielectric body as explained above, a high capacitance can be obtained when the multilayer electronic device is applied as a capacitor.
Preferably, a plurality of first through-hole electrodes and a plurality of second through-hole electrodes are formed in the dielectric body and the first through-hole electrodes and the second through-hole electrodes are arranged next to each other.
As explained above, when the first through-hole electrodes connected to the first internal electrodes and the second through-hole electrodes connected to the second internal electrodes are arranged next to each other in the dielectric body, an effect that magnetic flux cancels each other further improves due to high frequency currents flowing inversely to each other.
Preferably, each of the plurality of first through-hole electrodes is connected to all of the first internal electrodes arranged in the dielectric body and each of the plurality of second through-hole electrodes is connected to all of the second internal electrodes arranged in the dielectric body.
In this case, a connection area of the respective through-hole electrodes and respective internal electrodes increases.
Alternately, in the present invention, at least one of the plurality of first internal electrodes arranged in the dielectric body is not connected to at least one of the plurality of the first through-hole electrodes; and
at least one of the plurality of second internal electrodes arranged in the dielectric body is not connected to at least one of the plurality of the second through-hole electrodes.
In this case, alternately, the plurality of first internal electrodes arranged in the dielectric body have less connection points with the plurality of first through-hole electrodes on both end sides along the stacking direction of the dielectric layers and more connection points at the center portion; and
the plurality of second internal electrodes arranged in the dielectric body have less connection points with the plurality of second through-hole electrodes on both end sides along the stacking direction of the dielectric layers and more connection points at the center portion.
By changing the number of connection points of the through-hole electrodes connected to the internal electrodes in this way, the effect of magnetic flux cancellation can be furthermore expected and the parasitic induction further reduced, because the number of current fluxes alternately flowing in the direction of the thickness is increased.
Preferably, the dielectric body is formed to be a hexagonal shape;
at least two opposite sides of the dielectric body in the hexagonal shape are provided with base parts of the first and second terminal electrodes in the way of extending in parallel respectively with the first and second through-hole electrodes; and
the first and second terminal electrodes are connected respectively to the first and second through-hole electrodes at terminal pad portions bent at a right angle from the base parts of the first and second terminal electrodes.
When flowing high frequency currents to the terminal electrodes, as two kinds of internal electrodes connected to the terminal electrodes via the through-hole electrodes become anodes and cathodes, currents from the terminal electrodes on two sides mutually inversely flow to the internal electrodes, which brings an effect of reducing parasitic inductance.
Preferably, the first terminal electrodes connected respectively to the first through-hole electrodes and the second terminal electrodes connected to the second internal electrodes are arranged next to each other on the outer surface of the dielectric body.
In this case, since the currents flow so that polarities of adjacent terminal electrodes become different to each other, the effect of magnetic flux cancellation furthermore improves due to the high frequency currents flowing in the inversed directions to each other.